A. Technical Field
The present invention relates to a carrier band of a carrier tape system in which electronic parts are stuck to a tape band and rolled up to a reel.
B. Background Art
As the electronic industry develops and the automation progresses, the automatic mounting of the electronic parts becomes strongly required. And, as carrier bands of electronic parts, those of a carrier taping system increase in which high-speeding and making long are possible. Among taping systems, as the environmental preservation spreads globally, a sticking system becomes well evaluated in which decreasing of the public nuisance is possible.
Classifying roughly, as carrier systems of conventional carrier bands, an emboss system, a convexity system and a sticking tape system are used.
As shown in FIG. 5 (A), in the emboss system, a storing box 2 is emboss-formed to a tape band 1 and stores an electronic part A inside and is covered with a cover tape 3. In this system, sealing between the tape band 1 and the cover tape 3 is difficult. If the sealing is weak, the electronic part A springs out. If the sealing is strong, the cover tape 3 is not peeled off and is broken at the time of mounting. And, this system is various and lacks an adaptability. Also, this system needs a metal mold which increases a cost.
As shown in FIGS. 5 (B1) and (B2), in the convexity system, convexities 4 are formed on the tape band 1 at regular intervals and the electronic part A is fixed on the convexity with an adhesive. Therefore, when the electronic parts A are taken out, it is necessary to push up a pin 5 from the under side of the convexity 4 and thrust the electronic part A with the pin 5. And, in case of the thin electronic part, there is a possibility that the electronic part might be broken due to a shock of pushing up the pin 5.
As shown in FIGS. 5 (C1), (C2) and (D), in the sticking system, the tape band 1 has holes 6 at regular intervals, and a sticking face of a sticking tape 7 affixed to the back side of the tape band 1 is exposed to the holes 6, and the electronic parts A are stuck to this sticking face. This system is free-size style and has an advantage that many electronic parts can be taped and is superior to said emboss system and said convexity system.
By the way, in the sticking carrier tape system, the sticking tape is affixed to the back side of the tape board which has the holes at regular intervals as the sticking face is exposed to the holes, and is rolled up to a reel to complete the sticking carrier tape. Then, the sticking carrier tape is sent to a IC maker. In the IC maker, the carrier tape is rolled back and the electronic parts are stuck on the holes with a taping machine and rolled up to a reel and sent to a mounting user.
In the mounting user, the carrier tape with the electronic parts is rolled back and the electronic parts are absorbed with a mounting machine simultaneously with peeling off the stick tape from the back side of the tape band. The absorbed electronic parts are mounted on printed-circuit boards. Thus, the role of carrier tape is finished.
In most of sticking carrier system, the width of the holes is wider than the sticking tape and the sticking tape is affixed to the tape band so that there are openings at both sides of the holes. Other way of sticking carrier is seldom used.
The reason of making above openings is referred below. As shown in FIGS. 5 (C2) and (D), in the electronic part A, reed portions B hang downward from the body so that reeds do not rise at the time of soldering. The distance between the bottom of the body and a pointed end of the reed portion B is called stand-off S. Therefore, the bottom of the body is higher than the tape band 1 by stand-off S. It is necessary that the sticking tape 7 is stuck to the electronic part A as the sticking tape 7 is pushed up greatly from the lower side of the tape band 1 to the bottom of the body of the electronic part A and is extended. As shown in FIG. 6 (A) and (C), the openings 18 are made on both sides of the holes so that the sticking tape 7 is ready to extend.
There are problems listed below in above-mentioned carrier tape which has the openings 18 on both sides of the holes.
(1) In case of the electronic part A (IC) smaller than the hole 6, problems happen when the sticking tape 7 is peeled off from the back side at the time of peeling off of the part as the hole 6 is larger than the width of the sticking tape 7. When the part is larger than the hole, the tape supports the part. However, when the part is smaller than the hole, as shown in FIG. 6 (C), only the reed portions of the electronic part mount on the tape band. Therefore, the reed sometimes bends at the time of peeling off of the part as the reed portions do not have enough force to support the part. Furthermore, as shown in FIG. 6 (D), the part is not peeled off and thrust through with being stuck to the sticking tape. Also, when the part is peeled off from the tape band, the part is peeled off from the sticking tape by a peeling exfoliation. If the both sides of the part are openings, there is no position to support the part. Therefore, the part sometimes slip by the side force at the time of peeling off of the sticking tape. As mentioned above, there are cases in which the small parts can not be applied to by the carrier tape which has the openings 18 on both sides of the holes.
(2) The carrier tape is manufactured by affixing the sticking tape to the back side of the tape band. Even if the sticking tape is affixed to the center of the tape band, the sticking tape rises at first and becomes to attach with time as an exfoliation agent for peeling off is applied on the back side of the tape band. And, the sticking tape sometimes slip from the center as there is no support of the sticking tape at the time of rolling up to a reel. If the sticking tape meanders to one side of the holes, the openings are covered and the sticking tape does not rise. In that case, as the sticking area with the electronic parts decreases, the parts are not sometimes stuck and fall off to be a cause of troubles.
(3) In the carrier sticking tape, the adhesive is applied to a crape base considering an extension. When the part is stuck to the sticking tape, the sticking tape is pushed up greatly from a horizontal condition as FIG. 5 (C1) to a condition as FIG. 5 (C2) and is stuck to the part. Therefore, a great stress is applied to the sticking tape and the adhesive as well as the tape is extended and is thinned and the sticking force becomes weak. Furthermore, if the base made of Japanese paper is dried at the greatly extended condition after a moisture absorption, a strong shrinking force is applied to the base as "shoji" paper. And, if the shrinking force becomes stronger than the sticking force to the part, the part falls off and this becomes a big trouble. As mentioned above, there are cases in which the parts having a large stand-off can not be applied to by the carrier tape which has the openings 18 on both sides of the holes.
Also, when the adhesive is extended, the adhesive is apt to be influenced by the oxygen and the water in the air and changes in quality and returns to be gummous. Therefore, when the part is peeled off from the carrier tape at the time of mounting, the sticking tape becomes a gummous roping condition. As a result, the parts are not peeled off from the tape and the parts can not be absorbed. This big trouble has not been yet solved. Above problem can not be solved by the current system of forming the openings and pushing up the sticking tape and extending it greatly and sticking.
Therefore, it is planned to manufacture a carrier tape in which the sticking tape is pushed up beforehand to the upper side of the holes of the tape board having the holes. However, the carrier tape is rolled up to the reel after affixing the sticking tape and the board. Then, the carrier tape is sent to the IC maker. Therefore, if the sticking tape is only pushed up, the sticking tape is pressed down as a rolling pressure is applied for rolling up of the reel and as the pushed up sticking tape is not supported. And, in that case, the sticking tape is pushed back and is crushed out of shape and sticking faces are mutually stuck. Therefore, such a carrier tape is unable to be used and can not be put to practical use.
(4) A one-side sticking tape is rolled on the back side of the base with an exfoliation treatment. The tape is properly weighed not to fall loose. Therefore, the exfoliation force is necessary to roll back. However, the sticking tape is placed on the tape base and the tape base is rolled up to the reel at high speed at the time of manufacturing the carrier tape. Therefore, the sticking tape is apt to be extended according to the weight of the exfoliation force of the sticking tape. And, a big rolling pressure is applied to the direction of rolling up as a back tension is applied. Furthermore, the sticking face exposed from the holes is pressed down by the pressure and the sticking layer thins and the sticking force becomes weak according to be near to the center side. This becomes a cause of troubles.